Michael, you've written and covered so much on this topic, not elaborating a bit on something is no biggie!

Hey, what is the best and or most practical way to properly measure ride heights that would discount wheel/tire choice? I'd like to be able to discern how much I'm lowered other than what my tire option accounts for...

 

In my opinion, any hard point under the car...the jack points are probably okay except for those really serious racers. Unfortunately, inner pivot points become too close to the car's center line. I do use the jack points, but never any baody panels as these are subject to large build tolerances. Or, just make sure your adjustable coilovers are exactly the same left to right...as a beginning, cuz corner balancing will change these settings.

 

1 " and a slight rake .... Old pic- October

 

My car looks just like yours REDFURY but I recently lowered the backend a 1/4" more hoping to stabilize the car at threshold braking. On Tuesday I'll know if this was a good move...

Where are you located? I see lots of dead leaves on the ground...drought or Hickory trees above?

 

Does lowering the car any amount at all increase the roll couple?

Matt

 

Matma92ser,

Lowering your car might or might not adversely affect your roll couple.

Here's the deal: Any change in suspension geometry will strongly affect the roll couple, camber gain, and castor curve in MINI. Period. It takes very little in the way of change to completely nullify and even reverse the designed in and sophisticated suspension performance characteristics for MINI. That said, there are lots and lots of MINI enthusiasts who have totally altered their suspension geometry, who don't know it, and who are very satisfied and happy with their MINI's handling. Altering the roll couple, camber gain curve, and castor curve for the worse is not the end of the world, at least for MINI. Because of the MINI's wonderful chassis rigidity and other aspects of the suspension and steering design, MINI will still perform excellently. The only problem with ruining the roll couple, camber gain and castor curves is that real performance enthusiasts are leaving a lot of potential performance on the table.

Here is a run down of the ways to lower MINI and a description their effect on roll couple, etc. 1) lower MINI by using smaller wheels and tires. This lowering method does not change the suspension geometry and doesn't affect roll couple, etc. 2) lower MINI with shorter springs. This method results in profound effects on roll couple, etc. 3) lower MINI with shorter springs but alter the front control arm attachment points and make a bump steer correction to restore the "stock" suspension geometry. This method of lowering results in a normalization of the roll couple, etc and not compromise in the sophisticated suspension design. 4) lower MINI with shorter springs, keep the attachment points the in the stock locations, but install springs with a significantly higher spring rate and, likely, a thicker front anti-roll bar. This method of lowering is what a lot of people end up doing. The combination of the higher spring rates and a thicker anti-roll bar is effective at compensating for the vastly increased roll couple, etc and can make for a fine handling track / autocross car but with a certain compromise of streetability.

The bottom line is that there are a number of performance and aesthetic characteristics that determine whether lowering your MINI is perceived as a net gain or a net loss. The major changes in roll couple, camber gain, and castor curves that typically result from lowering your MINI even 1/2", in the real world of the casual enthusiast, are not detected and not really important in that context.

I hope this helps you,

John Petrich in Seattle

 

Michael, thanks for the input, I really appreciate it. I guess there is about .5" in ride height variation from the factory. Below are some rolling diameters, with stock, at least from a few years ago, in bold:

TIRE SIZE | DIAMETER
+-----------+-------------------+
195/55-15 | 23.44in (595.5mm)
205/40-17 | 23.46in (595.8mm)
215/50-15 | 23.46in (596.0mm)
215/45-16 | 23.62in (599.9mm)
195/50-16 | 23.68in (601.4mm)
185/60-15 | 23.74in (603.0mm)
215/40-17 | 23.77in (603.8mm)
205/55-15 | 23.88in (606.5mm)
215/35-18 | 23.93in (607.7mm)
175/65-15 | 23.96in (608.5mm)
225/45-16 | 23.97in (608.9mm)
205/50-16 | 24.07in (611.4mm)
225/40-17 | 24.09in (611.8mm)
225/35-18 | 24.20in (614.7mm)
195/60-15 | 24.21in (615.0mm)
205/45-17 | 24.26in (616.3mm)
215/55-15 | 24.31in (617.5mm)
195/55-16 | 24.44in (620.9mm)
185/65-15 | 24.45in (621.0mm)
215/50-16 | 24.46in (621.4mm)
215/45-17 | 24.62in (625.3mm)
==========================

Just some info that I wanted to share....

 

Tony,

Thanks - wow, up late last night?

John, and all,

Regarding roll couple:

If you take a ride in a bone stock S and then a ride in an S that is lowered by at least one inch - with or without a big rear swaybar - you can actually feel the greater roll force. I feel it every day...my car feels heavier. My car is actually more responsive than a stock S but it does not have that light, effortless touch it had while stock.

In addition, we do not posses all the computers and tools to accurately anaylize the exact increase in roll couple. We do know that heavier spring rates and dampers along with larger swaybars help to control roll couple. However, be aware that a portion of the benefit these new performance oriented components is consumed by controlling roll couple...ie, not directly aiding handling but controlling an newly inherited compromise.

This is one of the reasons I sort of dogged some spring manufactures for producing springs lighter than stock while also lowering the car. Progressive rate springs rate springs offer a great ride, but allow a liitle more intial roll rate as a compromise.

 

.... but this is where a sway bar and damper adjustments comes in Michael. I'm certainly not stating anything new to you here, but softer springs and a heavier bar and stiffer dampening and rebound and you might have a great car opposed to stiffer springs and softer bar and dampening. No?

 

Michael and all,

I agree that the altered roll couple will alter the handling but stated that "the casual enthusiast" might not notice or car about the difference. I didn't say that the casual enthusiast might even desire the difference.

A lot of people equate what they notice about the altered ride and new found steering clumsiness as signs of "high performance", and "race", even. These changes feed their dreams about making MINI "better" than the next persons.

So, the steering and chassis dynamic changes are present, not always recognized, and often interpreted as the opposite of what they really are.

John Petrich in Seattle

 

FWIW, I spoke with Way from Way Motorworks and Eric from Helix this past week... both are of the opinion that a bit of reverse-rake (rear lower than front) is a benefit for the MINI.

 

What "benefits" were they talking about?

John Petrich in Seattle

 

Michael, I was up to about 3 am that night! I lost my Nonna last week, and there has been much to do, besides grieve. For those non-Italians in the crowd: Nonna = Grandma.

I actually pondered a reverse rake, but only to help alleviate bump-stopping issues. For aerodynamic reasons, I can't imagine this otherwise being desirable, but I'm open to convincing . Whatever corner-balances me, I'm going to stick with that stance...

I would love to hear the reasoning for the reverse rake though!

Due to the aforementioned roll couple concerns, I'm contemplating raising my MINI a little. I'm over a half an inch lower simply because of my tire selection, but I know that I'm still lower than that; but I just don't know how much higher to go to get me to a more stock-like suspension geometry set-up....

 

Thanks John. I think in the context of this thread we are mainly talking about 2) and 4). Do we know for a fact that the roll couple will increase with any amount of lowering? Could it be possible that the roll couple will decrease up to a certain amount of lowering, and then begin to increase as the suspension is further lowered?

Matt

 

Unfortunately we didn't get into that level of detail... just that a bit of reverse rake improved handling. Way is doing quite well with this setup in his racing endeavors. I think he's currently 1st in whatever that US-based Mini racing series is... Mini World Challenge? Can't remember. Anyway, sorry there's no theory to back up the recommendation - I was just passing along what I heard from reputable sources.

 

I agree that there probably isn't any aerodynamic benefit from reverse rake, however, here are a few reasons why it shouldn't matter:
1. Our aerodynamics are so bad to start with
2. We're only talking about 1/4" to (at most) 1/2" of rake
3. If you're leaving the front ride height the same in either case (forward vs. reverse rake) and adjusting the rear relative to the front to dial in the rake it should be pretty much the same aerodynamically

I guess it boils down to whether the perceived aero benefit is because of (a) the rake angle of the car or (b) the "lowering affect" of dropping the front closer to the ground, which is independent from the rake variable.

Thoughts?

 

I agree with Onasled's comment, but the problem with softer springs is the static load will compress them more, and with the constrained travel with struts, you will have less travel (and required force) to bottom out. good for smooth track only, bad for the bumpy street.

 

From my readings, if the front end were up more, it would make for less downward force on the front drive wheels. I suppose this would be most apparent at higher speeds though. I'm thinking that those with lightened rear ends (I'm certainly in this group) can maybe benefit with a reverse rake due to the weight transfer to the rear. It would be neat to see the weight at each corner...

 

Yes, but keep in mind that the center of gravity and roll centers, therefore roll couple, also affect fore and aft weight displacement. There are also SVRC - side view roll centers and the placement of these control dive and squat but are also affected by the roll couple. Swaybars do little if anything to control dive and squat. In a real dynamic environment, the car is moving in many different directions within fractions of a second. Controling weight transfer is a key ingredient to better handling and in my humble opinion, it should be considered at a fundamental level. In the end, we may be left with a compromise, as is true with most of life. but at least we can consider ourselves learned and therefore better suited to leverage an unavoidable compromise.

I prefer - and I've written this plenty of times - to get me spring rates generally correct (generally refers to my street/track compromise) Springs should define the basic character of a car's handling - in sinc with other physical dimensions such as roll couple. Damping rates should then be selected to work a particular spring while offering some fine tuning potential and then swaybars should be used to fine tune springs and dampers. The driven venue will ultimately define what is used where. Race teams seldom use the same setup from on track to the next.

Softer is a hard term to qualify, but there are general rates that apply to road going cars, sporting cars, race cars and aero race cars. Within the previous, soft is obviously relative.

Dropping the center of gravity is the single best thing one can do for handling. But, with respect to our mini, doing so comes with a compromise. A large roll couple can only be controlled by increasing spring and damping rates in pitch, roll, dive, yaw. Swaybars will control larger roll couple in roll.

 

Most lowered suspensions have those increased spring and damping rates, as well as larger bars (at least in the rear). Since suspension lowering products generally increase spring and damper rates, could this be a moot point?

In your opinion, do the pros of lowering > 1" to drop the CG outweigh the cons for the street? How about the track?

 

pure&simple,

Good point, but not so moot.

There are a number of aftermarket products available now, and who knows will be available tomorrow, products that don't offer the spring rates, etc that we are discussing. There was a post on NAM a week or so ago by someone asking about lowering his car by cutting the springs. Good idea on the surface, but a lousy idea from the perspective of spring rates. Know of a recent local case where a BMW owner did just that and wouldn't understand why his car suddenly handled so "heavily" and rolled so much when he lowered it by cutting the springs.

I don't agree 100% with Michael about the benefits of lowering MINI. That said, mine is lowered almost 1". I don't know if lowering is the "best thing......", but, for the track, lowering MINI, along with the usual suspension, tire, and safety upgrades makes perfect sense. No question. It's just that I know some talented drivers who drive the stock set up so well that it makes me want to cry.

For the street, lowering MINI is cool. Lowering sure makes it a pleasure to look at the car, and I have zero problems with clearance and suspension travel. Blessed with a local road infrastructure that is in very good condition and I drive like a grandma.

So, increased spring rates might be part of a "survival package" for any MINI that is driven in a spirited manner in most real world situations. But, how high can and should we go with spring rates, for the street and for the track? Any ideas?

Regards,
John Petrich in Seattle

 

With my setup, PSS9s, front and rear H-Sport bars, my rear is slightly higher, with a lightened rear end ...

I can rotate the car at higher speeds by off throttle steering and straighten by throttle on

Watch my recent video from Mid-Ohio, car stays planted, I stay on the throttle in-exiting turns

I don't get loose unless I want to

 

Here's a FWD racer with reverse rake.
http://www.volkswagen.co.uk/vwracing/home

 

[B]

Hey John,

When I wrote lowering the CG is the single best thing one can do, I was thinking from the ideal - a clean sheet of paper type design, like an F1 car. I think you and I agree with repsect to road going fare; lowering the CG with springs alone is often a compromise.

Michael

 

John, I'm not sure if you saw this thread, but I'm curious to know how low you are from your from wheel centers (fronts) to the zenith of your arches. As Michael said, using trim is not the best, but it's easy!

I will measure mine later today. I know that from the ground-up, I'm at 22.5"

https://www.northamericanmotoring.co...arch+bump+leda